Modulation of rolling k vectors of angled gratings

ABSTRACT

Embodiments described herein relate to methods and apparatus for forming gratings having a plurality of fins with different slant angles on a substrate and forming fins with different slant angles on successive substrates using angled etch systems and/or an optical device. The methods include positioning portions of substrates retained on a platen in a path of an ion beam. The substrates have a grating material disposed thereon. The ion beam is configured to contact the grating material at an ion beam angle ϑ relative to a surface normal of the substrates and form gratings in the grating material.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/705,158, filed Dec. 5, 2019, which claims benefit of U.S. ProvisionalPatent Application Ser. No. 62/780,815, filed Dec. 17, 2018, which ishereby incorporated by reference herein.

BACKGROUND Field

Embodiments of the present disclosure generally relate to angled etchtools. More specifically, embodiments described herein provide forutilizing angled etch tools to form gratings having fins with modulatedslant angles.

Description of the Related Art

To form gratings with different slant angles on a substrate angled etchsystems are used. Angled etch systems include an ion beam chamber thathouses an ion beam source. The ion beam source is configured to generatean ion beam, such as a ribbon beam, a spot beam, or full substrate-sizebeam. The ion beam chamber is configured to direct the ion beam at anoptimized angle relative to a surface normal of a substrate. Changingthe optimized angle requires reconfiguration of the hardwareconfiguration of the ion beam chamber. The substrate is retained on aplaten coupled to an actuator. The actuator is configured to tilt theplaten, such that the substrate is positioned at a tilt angle relativeto an axis of the ion beam chamber. The optimized angle and tilt angleresult in an ion beam angle relative to the surface normal.

One example of a device that utilizes gratings with different slantangles is an optical device, such as a waveguide combiner. Opticaldevices may require gratings with slant angles that are differentdepending on the properties required for augmented reality.Additionally, gratings of an optical device may require gratings havingfins with slant angles to change, e.g., increase or decrease, across theregion to adequately control the in-coupling and out-coupling of light.Modulating the change in the slant angle of the fins, i.e. the rollingk-vector, using angled etch systems can be challenging.

Accordingly, what is needed in the art are methods of forming gratingswith having fins with modulated slant angles.

SUMMARY

In one embodiment, a grating forming method is provided. The methodincludes positioning a first portion of a substrate retained on a platenin a path of an ion beam with a first beam angle α. The substrate has agrating material disposed thereon. The ion beam contacts the gratingmaterial at a first ion beam angle ϑ relative to a surface normal of thesubstrate and forms one or more first gratings in the grating materialwith a first slant angle ϑ′. The first beam angle α is modulated to asecond beam angle α different that the first beam angle α. A secondportion of the substrate is positioned in the path of the ion beam witha second beam angle α. The ion beam contacts the grating material at asecond ion beam angle ϑ relative to the surface normal of the substrateand forms one or more second gratings in the grating material with asecond slant angle ϑ′ different than the first slant angle ϑ′.

In another embodiment, a grating forming method is provided. The methodincludes positioning a first portion of a substrate retained on a platenat a first tilt angle β relative to an x-axis of an ion beam chamber.The first portion of the substrate at the first tilt angle β ispositioned in a path of an ion beam generated by the ion beam chamberwith a beam angle α. The substrate has a grating material disposedthereon. The ion beam contacts the grating material at a first ion beamangle ϑ relative to a surface normal of the substrate and forms one ormore first gratings in the grating material with a first slant angle ϑ′.A second portion of the substrate is positioned at a second tilt angle βdifferent than the first tilt angle β. The second portion of thesubstrate at the second tilt angle β is positioned in the path of theion beam with the beam angle α. The ion beam contacts the gratingmaterial at a second ion beam angle ϑ relative to the surface normal ofthe substrate and forms one or more second gratings in the gratingmaterial with a second slant angle ϑ′.

In yet another embodiment, a grating forming method is provided. Themethod includes positioning a first portion of a substrate retained on aplaten in a path of an ion beam with a beam angle α. The substrate has agrating material disposed thereon. The ion beam is configured to contactthe grating material at an ion beam angle ϑ relative to a surface normalof the substrate and form one or more first gratings in the gratingmaterial. The substrate retained on the platen is rotated about an axisof the platen resulting in a first rotation angle ϕ between the ion beamand a grating vector of the one or more first gratings. The one or morefirst gratings have a first slant angle ϑ′ relative to the surfacenormal of the substrate. A second portion of the substrate is positionedin the path of the ion beam configured to form one or more secondgratings in the grating material. The substrate is rotated about theaxis of the platen resulting in a second rotation angle ϕ between theion beam and the grating vector of the one or more second gratings. Theone or more second gratings having a second slant angle ϑ′ relative tothe surface normal of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofits scope, and may admit to other equally effective embodiments.

FIG. 1A is a perspective, frontal view of a waveguide combiner accordingto an embodiment.

FIG. 1B is a schematic, cross-sectional view of a region of a waveguidecombiner according to an embodiment.

FIG. 2 is a side, schematic cross-sectional view of a variable angleetch system according to an embodiment.

FIG. 3 is a schematic, cross-sectional view of an electrode assemblyaccording to one embodiment.

FIG. 4 is a schematic, cross-sectional view of an electrode assemblyaccording to another embodiment.

FIG. 5 is a flow diagram of a method of forming gratings with rolling-kvector slant angles according to an embodiment.

FIG. 6 is a flow diagram of a method of forming gratings with rolling-kvector slant angles according to an embodiment.

FIG. 7 is a flow diagram of a method of forming gratings with rolling-kvector slant angles according to an embodiment.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments of the present disclosure generally relate to angled etchtools. More specifically, embodiments described herein provide forutilizing angled etch tools to form gratings having fins with modulatedor varied slant angles.

FIG. 1A is a perspective, frontal view of waveguide combiner 100. Thewaveguide combiner 100 includes an input coupling grating region 102 (afirst region) defined by a plurality of fins 108, an intermediategrating region 104 (a second region) defined by a plurality of fins 110,and an output coupling grating region 106 (a third region) defined by aplurality of fins 112. Each of the plurality of fins 108, 110 and 112are formed by a grating modulation process as described herein. Forexample, one or more of the plurality of fins 108, 110 and 112 aredifferent from the other fins within the same region. In one example,one or more of the plurality of fins 108 within the input couplinggrating region 102 has a different geometry, such as a different slantangle from that of other fins in that region. In addition, a slant angleof one discreet fin 108 within the input coupling grating region 102 maybe different across the length or width of the input coupling gratingregion 102. One or more of the plurality of fins 110 and 112 of theintermediate grating region 104 and the output coupling grating region106, respectively, may be formed to have a different geometry also.

FIG. 1B is a schematic, cross-sectional view of a region 101 of thewaveguide combiner 100. The region 101 may be one of the input couplinggrating region 102, the intermediate grating region 104, and the outputcoupling grating region 106.

The region 101 includes a grating material 103 disposed on a substrate105. The grating material 103 includes at least one of siliconoxycarbide (SiOC), titanium oxide (TiO_(x)), TiO_(x) nanomaterials,niobium oxide (NbO_(x)), niobium-germanium (Nb₃Ge), silicon dioxide(SiO₂), silicon oxycarbonitride (SiOCN), vanadium (IV) oxide (VOx),aluminum oxide (Al₂O₃), indium tin oxide (ITO), zinc oxide (ZnO),tantalum pentoxide (Ta₂O₅), silicon nitride (Si₃N₄), Si₃N₄ silicon-rich,Si₃N₄ hydrogen-doped, Si₃N₄ boron-doped, silicon carbon nitrate (SiCN),titanium nitride (TiN), zirconium dioxide (ZrO₂), germanium (Ge),gallium phosphide (GaP), poly-crystalline (PCD), nanocrystalline diamond(NCD), and doped diamond containing materials.

The grating material 103, in accordance with the methods describedherein, includes a plurality of fins 107 having two or more portions offins, such as a first portion of fins 109, a second portion of fins 111,and a third portion of fins 113. Each of the portions of fins has adifferent slant angle ϑ′ relative to a surface normal 115 of thesubstrate 105. In one embodiment, as shown, which can be combined withother embodiments described herein, the slant angle ϑ′ of the finsincreases across the substrate 105. In another embodiment, which can becombined with other embodiments described herein, the slant angle ϑ′ ofthe fins decreases across the substrate 105. The increase and ordecrease of the slant angle ϑ′ is also known as a rolling k-vector.

FIG. 2 is a side, schematic cross-sectional view of a variable angleetch system 200. It is to be understood that the variable angle etchsystem 200 described below is an exemplary variable angle etch systemand other variable angle etch systems, including angled etch systemsfrom other manufacturers, may be used with or modified to form gratingsand/or graded fins (one or more fins having a variable slant angle ϑ′ asopposed to other fins) on a substrate in accordance with the methodsdescribed herein. A controller 203 operable to control aspects of thevariable angle etch system 200 during processing.

To form gratings having fins with varied slant angles ϑ′, the gratingmaterial 103 is disposed on a substrate 105 is etched by the variableangle etch system 200. In one embodiment, which can be combined withother embodiments described herein, a patterned hardmask 213 is disposedover the grating material 103. The patterned hardmask 213 may be anopaque or non-transparent hardmask that is removed after the grating isformed. A transparent patterned hardmask (not shown) may remain afterthe grating is formed. The variable angle etch system 200 includes atriode extraction assembly 205. An ion beam housing 202 that houses anion beam source 204 is at least partially positioned in the ion beamhousing 202. The ion beam source 204 is configured to generate an ionbeam 216, such as a ribbon beam, a spot beam, or full substrate-sizebeam (e.g., a flood beam). The variable angle etch system 200 isoperable to direct the ion beam 216 at a beam angle α relative to asurface normal 115 of the substrate 105.

The substrate 105 is retained on a platen 206 in proximity to the ionbeam housing 202. The platen 206 is coupled to a scan and tilt actuator208. The scan and tilt actuator 208 is operable to move the platen 206in a scanning motion along a y-direction and a z-direction, and isoperable to tilt the platen 206, such that the substrate 105 ispositioned at a tilt angle β relative to the x-axis of the ion beamhousing 202. The beam angle α and tilt angle β result in an ion beamangle ϑ relative to the surface normal 115. To form gratings having aslant angle ϑ′ relative the surface normal 115, the ion beam source 204generates an ion beam 216 and the ion beam housing 202 directs the ionbeam 216 towards the substrate 105 at the beam angle α. The scan andtilt actuator 208 positions the platen 206 so that the ion beam 216contacts the grating material 103 at the ion beam angle ϑ and etchesgratings having a slant angle ϑ′ on desired portions of the gratingmaterial 103. A rotation actuator 220 is coupled to the platen 206 torotate the substrate 105 about the x-axis of the platen 206 to controlthe slant angle ϑ′ of gratings. In the methods described herein, theslant angles ϑ′ of the two or more portions of fins, such as a firstportion of fins 109, a second portion of fins 111, a third portion offins 113, are modulated for the rolling k-vector via modulating the beamangle α, the tilt angle β, and a rotation angle ϕ, or combinationsthereof.

In one embodiment, which can be combined with other embodimentsdescribed herein, the variable angle etch system 200 includes the triodeextraction assembly 205 operable to modulate and/or vary the beam angleα. The triode extraction assembly 205 may include at least one of aplurality of actuated deflector plates and an electrode set or assemblydescribed below. The triode extraction assembly 205 is positioneddownstream of the ion beam source 204.

FIG. 3 depicts a side sectional view of an exemplary electrode assembly300 that may be used as the triode extraction assembly 205 of FIG. 2 .The electrode assembly 300 may be adapted as a graded lensconfiguration. The electrode assembly 300 may include several sets ofelectrodes. For example, the electrode assembly 300 may include a set ofentrance electrodes 302, one or more sets of suppression electrodes 304(or focusing electrodes), and a set of exit electrodes 306. The exitelectrodes 306 may be referred to as ground electrodes. Each set ofelectrodes may have a space/gap to allow an ion beam 312 (e.g., a ribbonbeam, a spot beam, or full substrate-size beam) to pass therethrough.

In some embodiments, the entrance electrodes 302, the suppressionelectrodes 304, and the exit electrodes 306 are be provided in a housing308. A pump 310 may be directly or indirectly connected to the housing308. The pump 310 may be a vacuum pump for providing a high-vacuumenvironment or other controlled environment of a different vacuum level.In other embodiments, which may be combined with other embodiments, thehousing 308 may include one or more dielectric members 314. Thedielectric members 314 may be used to electrically isolate the housing308 from other components.

As shown in FIG. 3 , the set of entrance electrodes 302 and exitelectrodes 306 may include two conductive pieces electrically coupled toeach other. In other embodiments, the set of entrance electrodes 302 maybe a one-piece structure with an aperture for the ion beam 312 to passtherethrough. In some embodiments, upper and lower portions ofsuppression electrodes 304 may have different potentials (e.g., inseparate/discreet conductive portions) in order to deflect the ion beam312 passing therethrough. Although the electrode assembly 300 isdepicted as a seven (7) element lens configuration (e.g., with five (5)sets of suppression electrodes 304), it should be appreciated that anynumber of elements (or electrodes) may be utilized. For example, in someembodiments, the electrode assembly 300 may utilize a range of three (3)to ten (10) electrode sets. In some embodiments, the ion beam 312passing through the electrodes may include argon or other elements.

Electrostatic focusing of the ion beam 312 may be achieved by usingseveral thin electrodes (e.g., the suppression electrodes 304) tocontrol grading of potential along a path the ion beam 312. As a result,the use of input ion beams 312 may be used in an energy range that mayenable higher-quality beams, even for very low energy output beams. Inone embodiment, as the ion beam 312 passes through the electrodes of theelectrode assembly 300, the ion beam 312 may be decelerated from 6 keVto 0.2 keV and deflected at about 15 degrees to about 30 degrees, orgreater, by the electrodes of the electrode assembly 300. In oneexample, the energy ratio may be 30/1. In other embodiments, the inputpower may be 100 Volts to 3,000 Volts to deflect the ion beam 312 byabout 15 degrees to about 30 degrees, or greater.

It should be appreciated that separating and independently controllingdeceleration, deflection, and/or focus may be accomplished by one or acombination of moving the electrodes (e.g., the entrance electrode 302,suppression electrodes 304, and the exit electrode 306) with respect toa central ray trajectory of the ion beam 312, and varying deflectionvoltages electrodes (e.g., the entrance electrode 302, suppressionelectrodes 304, and the exit electrode 306) along the central raytrajectory of the ion beam 312 to reflect beam energy at each pointalong the central ray trajectory at a deflection angle 316. The symmetryof the electrodes with respect to the central ray trajectory of the ionbeam 312 is where the ends of upper and lower electrodes closest to theion beam 312 may be maintained at equal (or near-equal) perpendiculardistances from the central ray trajectory of the ion beam 312. Forexample, a difference in voltages on electrodes above and below the ionbeam 312 may be configured so that a deflection component of theelectric field may be a fixed ratio/factor of the beam energy at thatpoint (which may vary along the electrodes or lenses).

FIG. 4 is a schematic, cross-sectional view of an electrode assembly 400according to another embodiment that may be used as the triodeextraction assembly 205 of FIG. 2 . The electrode assembly 400 includesa pair of entrance electrodes 302 coupled to a first actuator 402, apair of suppression electrodes 304 coupled to a second actuator 405, anda pair of exit electrodes 306 (e.g., ground electrodes) coupled to athird actuator 410. The first actuator 402 is operable to move one orboth of the entrance electrodes 302 a first distance 415 from a midline420 to modulate the beam angle α of the ion beam 312. The secondactuator 405 is operable to move one or both of the suppressionelectrodes 304 a second distance 417 from the midline 420 to modulatethe beam angle α of the ion beam 312. The midline 420 corresponds to anormal of the ion beam 312 prior to modulation of the beam angle α ofthe ion beam 312 by one or more of the entrance electrodes 302, thesuppression electrodes 304 and the exit electrodes 306. The thirdactuator 410 is operable to move the one or both of the exit electrodes306 a third distance 425 from the midline 420 to modulate the beam angleα of the ion beam 312. The first actuator 402, the second actuator 405,and the third actuator 410 are coupled to the controller 203 operable tooperable to control aspects of the variable angle etch system 200 duringprocessing, such as the methods described herein. The controller 203 isconfigured to control voltages.

FIG. 5 is a flow diagram of a method 500 of forming gratings withrolling-k vector slant angles. To facilitate explanation, FIG. 5 will bedescribed with reference to FIGS. 2, 3 and 4 , as applicable. Referencesto an ion beam in the following may refer to the ion beam 216 of FIG. 2and/or the ion beam 312 of FIGS. 3 and 4 .

At operation 501, a first portion of a substrate 105 having a gratingmaterial 103 disposed thereon is positioned in a path of the ion beam.The ion beam with a first beam angle α contacts the grating material 103at an ion beam angle ϑ relative to a surface normal 115 of the substrate105 and forms one or more first gratings in the grating material 103having a first slant angle ϑ′. At operation 502, the first beam angle αis modulated to a second beam angle α different than the first beamangle α. The second beam angle α may be greater or less than the firstbeam angle α. At operation 503, a second portion of a substrate 105having the grating material 103 disposed thereon is positioned in thepath of the ion beam with the second beam angle α. The second beam angleα greater than the first beam angle α will result in one or more secondgratings in the grating material 103 having a second slant angle ϑ′greater than the first slant angle ϑ′. The second beam angle α less thanthe first beam angle α will result in a second slant angle ϑ′ less thanthe first slant angle ϑ′. At operation 504, the second beam angle α ismodulated to a third beam angle α different that the second beam angleα. At operation 505, a third portion of a substrate 105 having thegrating material 103 disposed thereon is positioned in the path of theion beam with the third beam angle α to form one or more third gratingsin the grating material 103 having a third slant angle ϑ′ different thanthe second slant angle ϑ′. In embodiments, which can be combined withother embodiments described herein, the first, second, and third beamangles α are modulated by at least one of a plurality of actuateddeflector plates and an electrode assembly 400 or the electrode assembly300 as described above.

In one example, the first actuator 402 moves the entrance electrode(s)302 a first distance 415 from the midline 420 to modulate the beam angleα of the ion beam 312 to modulate the beam angle α of the ion beam 312.Alternatively or additionally, the second actuator 405 moves thesuppression electrode(s) 304 a second distance 417 from the midline 420to modulate the beam angle α of the ion beam 312. Alternatively oradditionally, the third actuator 410 moves the exit electrode(s) 306 athird distance 425 from the midline 420 to modulate the beam angle α ofthe ion beam 312. The modulation of the beam angle α changes the slantangle ϑ′ of the fins as described above.

In another example, which may be utilized alone or in combination withthe example above, deflection voltages of the electrodes (e.g., theentrance electrode(s) 302, suppression electrode(s) 304 (or focusingelectrode(s)), and the exit electrode(s) 306) may be varied to producevarying slant angles ϑ′ of the fins as described above.

FIG. 6 is a flow diagram of a method 600 of forming gratings withrolling-k vector slant angles. To facilitate explanation, FIG. 6 will bedescribed with reference to FIG. 2 . However, it is to be noted that anangled etch system other than the variable angle etch system 200 may beutilized in conjunction with the method 600. In other embodiments, whichcan be combined with other embodiments described herein, the method 600is performed by an ion beam etch system. References to an ion beam inthe following may refer to the ion beam 216 of FIG. 2 and/or the ionbeam 312 of FIGS. 3 and 4 .

At operation 601, a first portion of a substrate 105 having a gratingmaterial 103 disposed thereon is positioned in a path of the ion beam.The substrate 105 is positioned at a first tilt angle β relative to thex-axis of the ion beam housing 202. The ion beam with a beam angle αcontacts the grating material 103 at an ion beam angle ϑ relative to asurface normal 115 of the substrate 105 and forms one or more firstgratings in the grating material 103 having a first slant angle ϑ′. Atoperation 602, the first tilt angle β is modulated to a second tiltangle β different that the first tilt angle β. The second beam tiltangle β may be greater or less than the first tilt angle β. At operation603, a second portion of a substrate having the grating material 103disposed thereon is positioned in the path of the ion beam with the beamangle α. The second tilt angle β greater than the first tilt angle βwill result in one or more second gratings in the grating material 103having a second slant angle ϑ′ greater than the first slant angle ϑ′.The second beam angle α less than the first beam angle α will result ina second slant angle ϑ′ less than the first slant angle ϑ′. At operation604, the tilt angle β is modulated to a third tilt angle β differentthat the second tilt angle β. At operation 605, a third portion of asubstrate having the grating material 103 disposed thereon is positionedin the path of the ion beam with the beam angle α to form one or morethird gratings in the grating material 103 having a third slant angle ϑ′greater than the second slant angle ϑ′. In embodiments, which can becombined with other embodiments described herein, scan and tilt actuator208 moves the platen 206 in a scanning motion along at least one of ay-direction and a z-direction, tilts the platen 206 at the first,second, and third tilt angles β relative to the x-axis of the ion beamhousing 202.

FIG. 7 is a flow diagram of a method 700 of forming gratings withrolling-k vector slant angles. To facilitate explanation, FIG. 7 will bedescribed with reference to FIG. 2 . However, it is to be noted that anangled etch system other than the variable angle etch system 200 may beutilized in conjunction with the method 700. In other embodiments, whichcan be combined with other embodiments described herein, the method 700is performed by an ion beam etch system. References to an ion beam inthe following may refer to the ion beam 216 of FIG. 2 and/or the ionbeam 312 of FIGS. 3 and 4 .

At operation 701, a first portion of a substrate 105 having a gratingmaterial 103 disposed thereon is positioned in a path of an ion beam.The ion beam with the beam angle α contacts the grating material 103 atan ion beam angle ϑ relative to a surface normal 115 of the substrate105 and forms one or more first gratings in the grating material 103.The substrate 105 is positioned at a first rotation angle ϕ between theion beam and a grating vector of the one or more first gratings. Thefirst rotation angle ϕ is selected to result in the one or more firstgratings having a first slant angle ϑ′ relative to the surface normal115 of the substrate. The first rotation angle ϕ is selected by therotation angle ϕ equation of ϕ=cos⁻¹(tan(ϑ′)/tan(ϑ)). At operation 702,a second portion of a substrate 105 having the grating material 103disposed thereon is positioned in a path of the ion beam with the beamangle α. The ion beam contacts the grating material 103 at the ion beamangle ϑ relative to a surface normal 115 of the substrate 105 and formsone or more first gratings in the grating material 103. The substrate105 is positioned at a second rotation angle ϕ between the ion beam anda grating vector of the one or more second gratings. The second rotationangle ϕ is greater than the first rotation angle ϕ is selected to resultin the one or more second gratings having a second slant angle ϑ′greater than the second slant angle ϑ′. At operation 703, a thirdportion of a substrate 105 having the grating material 103 disposedthereon is positioned in the path of the ion beam with the beam angle α.The ion beam contacts the grating material 103 at the ion beam angle ϑrelative to a surface normal 115 of the substrate 105 and forms one ormore first gratings in the grating material 103. The substrate 105 ispositioned at a third rotation angle ϕ between the ion beam and agrating vector of the one or more second gratings. The third rotationangle ϕ is greater than the second rotation angle ϕ is selected toresult in the one or more third gratings having a second slant angle ϑ′different than the second slant angle ϑ′. In other embodiments, whichcan be combined with other embodiments described herein, the rotationactuator 220 rotates the substrate 105 about the x-axis of the platen206 to the first, second, and third rotation angles ϕ. The thirdrotation angle ϕ may be greater than the second rotation angle ϕ and thesecond rotation angle ϕ may be greater than the first rotation angle ϕ.The first rotation angle ϕ may be greater than the second rotation angleϕ and the second rotation angle ϕ may be greater than the third rotationangle ϕ.

In summation, methods of forming gratings with rolling-k vector slantangles on a substrate are provided. The methods described herein may beperformed in combination such that a rolling k-vector of the slantangles ϑ′ of the two or more portions of gratings is provided by atleast two of modulating the beam angle α, the tilt angle β, and arotation angle ϕ for portions of a substrate.

While the foregoing is directed to examples of the present disclosure,other and further examples of the disclosure may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A device comprising: A substrate having adiscrete input coupling region, a discrete intermediate coupling region,and a discrete output coupling region, each of the regions having aplurality of optical device fins disposed on the substrate, theplurality of optical device fins of each region comprising: at least onefirst optical device fin having a first slant angle; at least one secondoptical device fin having a second slant angle different than the firstslant angle; and at least one third optical device fin having a thirdslant angle different than the first slant angle and the second slantangle, wherein: the second slant angle is greater than the first slantangle and the third slant angle is greater than the second slant angle;or the first slant angle is greater than the second slant angle and thesecond slant angle is greater than the third slant angle.
 2. The deviceof claim 1, wherein each of the at least one first optical device fincorresponds to a first portion of optical device fins, the at least onesecond optical device fin corresponds to a second portion of opticaldevice fins, and the at least one third optical device fin correspondsto a third portion of optical device fins.
 3. The device of claim 1,wherein the first, second, and third slant angles correspond to arolling k-vector across a surface of the substrate.
 4. The device ofclaim 1, wherein the plurality of optical device fins include at leastone of silicon oxycarbide (SiOC), titanium oxide, titanium oxidenanomaterials, niobium oxide, niobium-germanium (Nb₃Ge), silicon dioxide(SiO₂), silicon oxycarbonitride (SiOCN), vanadium (IV) oxide, aluminumoxide (Al₂O₃), indium tin oxide (ITO), zinc oxide (ZnO), tantalumpentoxide (Ta₂O₅), silicon nitride (Si₃N₄), Si₃N₄ silicon-rich, Si₃N₄hydrogen-doped, Si₃N₄ boron-doped, silicon carbon nitrate (SiCN),titanium nitride (TiN), zirconium dioxide (ZrO₂), germanium (Ge),gallium phosphide (GaP), poly-crystalline (PCD), nanocrystalline diamond(NCD), or doped diamond containing materials.